Rolling link bicycle chain



Oct. 3, 1967 M. MORSE ROLLING LINK BICYCLE CHAIN 2 Sheets-Sheet 1 FiledJan. 9, 1967 i m s H we Oct. 3, 1967 M. MORSE 3,344,677

ROLLING LINK BICYCLE CHAIN Filed Jan. 9, 1967 2 SheetsSheet 2 UnitedStates Patent 3,344,677 ROLLING LINK BICYCLE CHAIN Milton Morse, 1Horizon Road, Fort Lee, NJ. 07024 Filed Jan. 9, 1967, Ser. N0. 608,200 1Claim. (Cl. 74--Z19) ABSTRACT OF THE DISCLOSURE A rolling link bicyclechain in which the clearance eX- isting between the bore in the bushingof each link and the cylindrical outer surface of the mating pin issufficiently great to allow the pin to rotate on the surface of the boreas the chain exhibits articulation as it passes over and from asprocket, where said sprocket is of predetermined pitch with said chainunder tension having a pitch in excess of said given pitch, and in theabsence of tension having a pitch less than said given pitch.

This application is a continuation-in-part of my copending application,Ser. No. 523,424; filed Jan. 27, 1966, under the same title.

This invention relates generally to the field of sprocket chains, of thetype usually employed in transmitting torque from a bicycle crank to adriven sprocket on the rear axle, and more particularly to improvedforms thereof which may operate satisfactorily in the absence of anyexternally applied lubrication.

In my co-pending application for Letters Patent, Ser. No. 478,212; filedAug. 9, 1965, entitled, Chain and Sprocket for Derailleur Mechanisms,there is disclosed an offset type chain which is relatively free ofbinding at each link interconnection thereof, rather than at eachalternate link interconnection as is the case with conventional linkchains. The present disclosure relates to a still further improvedconstruction and by which not only all of the advantages inherent in theconstruction disclosed in the above mentioned application are obtained,but the need for lubrication may be substantially eliminated withconsequent advantages.

It has long been known that bicycle chains tend to slip over the smallerdiameter sprockets when the bicycle rider bears down upon the' pedals.It has also been known that after some use the chain stretches a smalldegree, and the tendency to slip is considerably reduced. After stillfurther usage, the chain length increases still further, due to wear,and the slipping condition recurs. I have also observed that due to thestructure of the bicycle chains, each alternate link tends to slip overthe smaller sprockets because these alternate links are stiffest whenthe normal tension traps the bushing of that link between the sprockettooth and the pin of the preceding link. The fact that some of thesechains have a roller on the outside of the bushing does very little torelieve this condition. By the same occurrence, the pin and bushingrelationship in each odd chain link is such that the bushing is notunder pressure against the pin. The odd links are therefore loose andfree to drape properly around the smaller sprocket wheels.

By using an offset chain, it is possible to reproduce the odd chain linkcondition on all of the chain links, provided the chain is installed inthe proper direction relative to torque and drag. By using a slightlyoversized pitch, it becomes facilitated for the offset chain to flexproperly and easily onto the larger sprocket. Simply moving the centerto center distance of each link further apart does not accomplish this,because a chain of this type would have an additive error, and the chainwould not fit into the tooth pattern of the large chain wheel. However,

Patented Oct. 3, 1967 the condition can be accomplished by using alarger clearance between the outside diameter of the pins by which thelinks are interconnected and the inside diameter of the bushingssurrounding them. By combining these tWo factors, the result is a chainwhich does not slip on small sprockets and yet is free to bend properlyonto large sprockets.

It is therefore among the principal objects of the present invention toprovide an improved form of offset sprocket chain suitable for use in awide variety of applications in which the elimination of the need forlubrication is desirable.

Another object of the invention lies in the provision of an improvedsprocket chain which is incapable of binding when under tension at anylink interconnection.

A further object of the invention lies in the provision of an improvedsprocket chain possessed of the above advantages, in which the cost offabrication may be of a reasonably low order, and directly comparablewith prior art constructions, thereby permitting consequent wide sale,distribution and use.

A further object of the invention lies in the provision of an improvedsprocket chain of the class described which may be installed uponexisting sprocket gears and hubs without modification thereof.

A further object of the invention lies in the provision of a bicyclechain which may be well suited for derailleur mechanisms as well asother more conventional applications.

A feature of the disclosed embodiment lies in the fact that operationalnoise is substantially no higher than that encountered in usingconventional constructions.

Another advantage of the disclosed embodiment lies in the fact that withadditional clearance between the pins and bushings comprising the chain,particles of dirt and grit do not cause any individual link to becomestiff, the additional clearance also permitting a slight degree ofrolling action to take place, rather than mere pivoting action, with aconsequent reduction in friction.

Another feature of the invention lies in the fact that by virtue of theabove described rolling action, it is now possible to use much harderlubricants in lieu of the soft greases and oils which are normallyemployed on chains, with a further reduction of the problem of dirt,since dirt does not readily adhere to harder lubricants.

These objects and features, as well as other incidental ends andadvantages, will more fully appear in the progress of the followingdisclosure, and be pointed out in the appended claims.

In the drawing, to which reference will be made in the specification,similar reference characters have been em ployed' to designatecorresponding parts throughout the several views.

FIGURE 1 is a fragmentary sectional view of a first embodiment of theinvention, showing a chain in installed condition upon a drivingsprocket and driven sprocket.

FIGURE 2 is a fragmentary view in elevation of the first embodiment,partly in section, of a sprocket chain, as seen from the plane 22 inFIGURE 1.

FIGURE 3 is a fragmentary sectional view showing a modified form of thefirst embodiment.

FIGURE 4 is a fragmentary sectional view, corresponding to that seen inFIGURE 1, but showing a second embodiment of the invention.

FIGURE 5 is a fragmentary enlarged sectional view, partly in elevation,as seen from the plane 55 in FIG- URE 4.

FIGURE 6 is a schematic side elevationoal view of the second embodiment,showing the clearance between the rotating parts thereof.

In accordance with the first embodiment of the invention, the device,generally indicated by reference character 10, is illustrated inoperative association with a driving sprocket 11 and a driven sprocket12 (see FIG- URE 1).

As more fully described in my co-pending application, Serial Number478,212, referred to hereinabove, the chain includes a plurality ofoffset side plates 13, each plate having an outwardly disposed portion14, an offset portion 15, an inwardly disposed portion 16, as well asopenings 17 in the portions 14 and openings 18 in the portions 16.

Extending through the openings 17 and 18 which are placed in overlappedrelation are transversely disposed pins 19 having an outer surface 20.Surrounding the pins 19 are rollers 21 which may include integralbushing portions 21a. The rollers 21 are bounded by an inner surface 22and an outer surface 23, the former contacting the surfaces of therespective pins 19, and the latter contacting the teeth of the sprockets11 and 12.

In FIGURE 1 there is illustrated a typical installation of the device 10upon a bicycle (not shown), the driving sprocket having approximately 45teeth, while the driven sprocket, particularly in the case of aderailleur mechanism may have as little as 7 teeth in the smallest(highest) gear ratio.

It will be observed that the diameter of the pins 19 is substantiallysmaller than the diameter of the inner surface 22 of the rollers 21.This difference is substantially exaggerated for purposes of clarity,and in most cases, for example that described above wherein the drivingsprocket has approximately 45 teeth, the total clearance, that is to saytwice the difference of the respective diameters may be approximately.008 inch. This clearance will vary with the size of the chain involved,and as will more fully appear hereinbelow, it will also vary with thedegree of angular change of each link upon engaging the drivingsprocket.

Referring to the lefthand portion of FIGURE 1, it will be observed thatwith a 7 foot sprocket, the angular change between adjacent links uponengaging and disengaging the sprocket will be approximately 51.4degrees. However, it will be observed that the lower portion of thechain, prior to engaging the driven sprocket is relatively slack, sincetorque is transmitted on the upper segment thereof. Once engaged uponthe sprocket, tension is transmitted not through the pins 19, but ratherthrough the rollers which are firmly engaged in the interstices betweenthe sprocket teeth. Thus, by the time substantial angular displacementtakes place, the problem of friction between the pins and the rollersdoes not occur, this being dia grammatically illustrated by the placingof the pins in the center of the clearance opening in the bushings, asshown at reference characters 30, 31, and 32. When disengagement occurs,the link being disengaged is directly in line with the axis of the forcetransmitted by the driving sprocket 11 (see reference character 34), sothat no relative movement between the rollers and the pins occurs atthis point. Further examination of FIGURE 1 discloses displacement ofthe pins to the left of the center of the bushing with maximum clearanceappearing to the right of the pin. This is accounted for by the chainunder tension. This condition prevails until the point indicated byreference character 12 prime (that is to say the top dead center tooth)is reached.

Where the chain is fully engaged upon the sprocket 12, the pinsindicated at reference characters 30 and 31 are generally centrallydisposed because of the lack of tension in the chain itself.

In the segment below the sprocket 12, the weight of the chain causes avery small degree of tension, thus displacing the pins rightwardly, asseen in FIGURE 1 with respect to the bushing. However, because of thelight tension involved, the friction involved is correspondingly light.

Referring to the righthand portion of FIGURE 2, upon engagement with thedriving sprocket 11, a deflection between adjacent links will occurduring a period in which the surface of the pin is pressed against theinner surface of the roller. However, as indicated in the drawing, owingto the larger diameter of the driving sprocket, this deflection issubstantially smaller, and for the driving sprocket and chaincombination illustrated, the same amounts to only 8 degrees. Thus, thepin and roller are able to execute a small rolling motion through thisdegree of arcuate displacement without any relative sliding movement.Further rolling movement would be impossible with the degree ofclearance illustrated, but adequate rolling under tension is possiblebefore binding occurs. For this reason, little if any lubrication isneeded, as the pure rolling motion involved is relatively frictionless.

Where the difference in the number of teeth between the driving sprocketand driven sprocket is less, the clearance between the pins and bushingsmust be correspondingly greater, but for most combinations, a purerolling under tension upon engagement with the driven sprocket isusually possible.

Turning now to FIGURE 3 in the drawing, there is illustrated analternate form of the embodiment, in which, to avoid needlessrepetition, certain of the component parts thereof have been designatedby similar reference characters with the additional prefix 1.

The alternate form of the embodiment differs from the principal form inthat each of the side plates 113 is formed in such manner that theopenings 118 in the portions 116 are modified to includecylindrically-shaped flanges 11811 which are formed by drawing the metalremoved to form the opening inwardly. The effect of this construction isto grip the inner surfaces of the rollers 121 so as to prevent relativerotation therebetween.

The elimination of the heretofore loose rollers reduces the number ofmoving parts where abrasive dirt customarily collects, and accordinglythe useful life of the chain is extended.

Turning now to the second embodiment of the invention, as illustrated inFIGURES 4, 5 and 6, parts corresponding to those of the principalembodiment have been designated by similar reference characters with theadditional prefix 2.

In the second embodiment, the rolling effect occurring in the firstembodiment is further enhanced by deliberately undersizing the pins 19,and enlarging the diameter of the inner surface 122 of the bushings (seeFIGURE 6). Assume that the pitch of the sprocket is .500". By making thediameter of the pins .132", and the inside diameter of the bushing.140", the offset of the pin with respect to its center will be .00 andthat of the bushing with repsect thereto will be .008". By constructingthe links to have a center distance of .498, under tension, the truepitch will be .502" or .00 greater than the pitch of the sprocket.

Thus, once the chain is trained upon the sprocket, it will no longer beunder tension and can flex with very little friction. 'In the area priorto engagement with the small sprocket, it is also under little tensionand can fiex properly to readily engage the small sprocket.

I wish it to be understood that I do not consider the invention limitedto the precise details of structure shown and set forth in thisspecification, for obvious modifications will occur to those skilled inthe art to which the invention pertains.

Iclaim:

The combination of a driven sprocket, a driving sprocket, and an offsetsprocket chain including a plurality of pivotally interconnected links,each of said links including a pair of offset plates having relativelyinwardly and outwardly disposed portions in parallel relation, therebeing openings in each of said inwardly and outwardly disposed portions,pins extending through and maintained within a plurality of alignedopenings in adjoining links, and roller members surrounding said pins,the improvement comprising: said pins having an outer surface, saidrollers having an inner surface, there being a sufficient clearancebetween said last mentioned surfaces to permit a limited degree ofrolling motion therebetween, said clearance being sufiicient to allowpure rolling motion between said pins and said rollers over the relativeangular displacement of a pair of adjoining links upon enteringengagement with said driven sprocket, said driven sprocket being ofpredetermined pitch, and said chain under tension having a pitch inexcess of said given pitch, and in the absence of tension having a pitchless than said given pitch.

References Cited UNITED STATES PATENTS 6/ 1926 Weiss 74-245 12/1939McAninch 74-245 9/1953 Van Doren 74245 X 6/1961 Mazzarins 74-250 6/ 1964 Rudolph 74255 FOREIGN PATENTS 4/ 1964 Great Britain.

FRED =C. MATTERN, JR., Primary Examiner. J. A. WONG, Assistant Examiner.

